Wind rips across an isolated utility station in northwestern China’s desolate Gansu Corridor. More than 2,000 years ago, Silk Road traders from Central Asia and Europe crossed this arid, narrow plain, threading between forbidding mountains to the south and the Gobi Desert to the north, bearing precious cargo bound for Imperial Beijing. Today the corridor carries a distinctly modern commodity: gigawatts of electricity destined for the megacities of eastern China. One waypoint on that journey is this ultrahigh-voltage converter station outside the city of Jiuquan, in Gansu province.
Electricity from the region’s wind turbines, solar farms, and coal-fired power plants arrives at the station as alternating current. Two dozen 500-metric-ton transformers feed the AC into a cavernous hall, where AC-DC converter circuits hang from the 28-meter-high ceiling, emitting a penetrating, incessant buzz. Within each circuit, solid-state switches known as thyristors chew up the AC and spit it out as DC flowing at 800 kilovolts.
From here, the transmission line traverses three more provinces before terminating at a sister station in Hunan province, more than 2,300 kilometers away. There, the DC is converted back to AC, to be fed onto the regional power grid. The sheer scale of the new line and the advanced grid technology that’s been developed to support it dwarf anything going on in pretty much any other country. And yet, here in China, it’s just one of 22 such ultrahigh-voltage megaprojects that grid operators have built over the past decade.
The result is an emerging nationwide supergrid that will rectify the huge geographic mismatch between where China produces its cleanest power — in the north and west — and where power is consumed in the densely populated east. Moving energy via this supergrid will be crucial to maximizing China’s use of renewable energy and slashing reliance on coal.
Read on at IEEE Spectrum